Supramolecular Arrays Based on Dimetal Building Units

Supramolecular chemistry is today a major thrust area, a significant part of which is based on the use of metal atoms or ions as key elements in promoting the assembly of and dictating the main structural features of the supramolecular products. Most of the work has been done with single metal atoms or ions in this role, but considerable success has already been achieved by employing M-M bonded dimetal entities instead. We review here the work done in our laboratory. Metal-metal bonded cationic complexes of the M(2)(DAniF)(n)(MeCN)(8-2n)((4-n)+) type, where M = Mo or Rh and DAniF is an N,N'-di-p-anisylformamidinate anion, have been used as subunit precursors and then linked by various equatorial and axial bridging groups such as polycarboxylate anions, polypyridyls, and polynitriles. Characterization of the products by single-crystal X-ray diffraction, CV, DPV, NMR, and other spectroscopic techniques has revealed the presence of discrete tetranuclear (pairs or loops), hexanuclear (triangles), octanuclear (squares), and dodecanuclear (cages) species and one-, two-, or three-dimensional molecular nanotubes. These compounds display a rich electrochemical behavior which is affected by the nature of the linkers.